鳞片石墨对环氧涂层强度和吸水性能的影响

Influence of graphite flake on the strength and water absorption of epoxy coating

分别研究了含不同质量分数鳞片石墨的环氧涂层的剪切强度以及经冷热水循环浸泡后涂层的重量吸水率与浸泡时间、浸泡72h后涂层的体积变化率、密度和鳞片石墨质量分数的关系。结果表明,随着石墨含量的增加,涂层剪切强度急剧降低,在w(石墨)=10%处达最低值,之后逐渐升高。当w(石墨)=20%时,涂层剪切强度较大。涂层重量吸水率随浸泡时间的增加而增大,并呈现周期性变化(以每24h为周期)。同时,随着石墨含量的增大,涂层吸水率降低。不同石墨含量的涂层浸泡72h后其体积变化率随石墨含量的增加呈现双峰特征,当w(石墨)=20%时,其体积变化率较低,为2.8%。浸泡前和浸泡72h后,涂层密度随石墨含量的增加均呈现先下降后增大的趋势,而且,两者在石墨含量为5%处的密度几乎相等。解释了涂层中不同石墨含量对其强度和耐水性的影响。涂层中适宜的石墨含量为20%。

The shear strength of epoxy coat containing different mass fraction of graphite flake, relationship of eoating＇s by-weight water absorption rate with dipping time and relationship of coating＇s volume change rate, density with mass fraction of graphite flake after a dipping time of 72 h were studied respectively by cycle dipping using cold and hot water, Results show that the shear strength of epoxy coating decreases rapidly with increasing content of graphite flake and it reaches the lowest value with a content of 10% of graphite flake. Then it increases gradually. Shear strength is larger at w （graphite flake ） = 20%. The byweight water absorption rate increases and presents periodic variation （ by a cycle of 24 h） with increasing dipping time. Meanwhile coating＇s water absorption rate decreases with increasing content of graphite flake. The volume change rates of coatings containing different content of graphitc flake present two characteristic peaks with increasing content of graphite flake after a dipping time of 72 h. The volume change rate has a lower value of 2.8% at w（ graphite flake） = 20%. Both coatings density is decreasing firstly and then increasing with the increase of graphite content before dipping and after dipping for 72 h. And density values are about equal at 5% content of graphite flake. Influences of different content of graphite flake in coating on its strength and water resistance were described. The suitable content of graphite flake is 20%.